Neuromuscular basis for ventricular fold function

Area of Science:

• Laryngology
• Neuroanatomy
• Vocal Fold Physiology

Background:

• The precise neuromuscular control of ventricular folds remains unclear, with ambiguity regarding their active or passive contraction.
• Understanding ventricular fold function is crucial for phonation, pressure regulation, and post-laryngeal surgery outcomes.

Purpose of the Study:

• To elucidate the neuromuscular mechanisms underlying ventricular fold function.
• To determine if ventricular fold contraction is an active or passive process.
• To identify the specific musculature and innervation involved.

Main Methods:

• Histological analysis of human larynx sections from a patient with unilateral vocal fold paralysis, comparing paralyzed and unaffected sides.
• Electrophysiological studies in a porcine model, stimulating the superior laryngeal nerve and recording from ventricular folds.
• Assessing changes in ventricular fold electrical activity after recurrent laryngeal nerve transection.

Main Results:

• Histology revealed muscle atrophy in the ventricularis and thyroarytenoid on the paralyzed side, with normal muscle size on the unaffected side.
• Electrophysiology confirmed innervation of the ventricularis muscle by the recurrent laryngeal nerve.
• Ventricularis muscle activity was directly associated with ventricular fold contraction.

Conclusions:

• Ventricular fold adduction is an active muscular contraction.
• The ventricularis muscle is responsible for ventricular fold adduction.
• Recurrent laryngeal nerve activity mediates ventricularis muscle contraction and subsequent ventricular fold adduction.